The present invention relates to a foodstuff container and, more particularly, to a container using an exothermic reaction agent for heating the contained foodstuff such as Japanese Sake, coffee, soup, noodles and the like, without the supply of external thermal energy.
It is known to warm the foodstuff by utilizing heat generated by a chemical exothermic reaction such as hydration between quick lime (calcium oxide) and water as disclosed in, for example, U.S. Pat. No. 2,288,895, U.S. Pat. No. 3,369,369, Japanese Utility Model Publication No. 57-2867, Japanese Utility Model Applications as laid open under No. 59-101882, No. 59-162826, No. 59-162828, No. 59-171629 and No. 60-70235. In any of these prior art references, the reaction agent is incorporated in a container body. When it is desired to initiate the exothermic reaction, the reaction inducing liquid is mixed with the agent either by supplying the liquid from outside the container body, as typically disclosed in Japanese Utility Model laid open under No. 59-101882, or by rupturing a liquid bag incorporated in the container body by means of a needle member, as typically disclosed in Japanese Utility Model laid open under No. 60-70235. The self-heating container of the latter type has eliminated the inconvenience of carrying a water bottle, for example, in addition to the container itself.
However, the self-heating container of the above type has the following problems. That is, the exothermic reaction, particularly the hydration between the quick lime and water is very active and is initiated immediately after the quick lime is mixed with the water, with resultant generation of expanded hot gases including steam. If the water of a quantity necessary for causing the reaction with all of the quick lime contained is supplied at once, there is very rapidly generated a large amount of hot gases, a part of which sometimes spouts from the container body with non-reacted water. This not only involves a danger to the body and clothes of the user but also decreases efficiency due to a shortage of the quantity of water required for the contained amount of quick lime. The above prior art arrangement is never free from these disadvantages because all of the liquid is supplied to the quick lime at a moment that the bag is manually ruptured.
Further, the self-heating containers of the above prior art arrangement are designed to generate substantially a constant quantity of thermal energy. Therefore, the temperature of the heated foodstuff depends on the initial temperature of the foodstuff which, in turn, depends on the ambient temperature. For instance, presuming that the contents, i.e. the foodstuff, can be suitably taken at temperature of around 40.degree. C. to 45.degree. C., and if the container is so designed that the contents can be heated to such temperature when used in an ambient temperature of 0.degree. C. to 5.degree. C., the contents would be excessively heated up to 65.degree. C. when the container is used in an ambient temperature of around 25.degree. C. On the other hand, if the container is designed so as to raise the temperature of the contents by about 20.degree. C. to 25.degree. C., the contents could be heated only to at most 30.degree. C. when the container is used in an ambient temperature of 0.degree. C. to 5.degree. C.
The above problems could be removed by providing several kinds of containers each having a different volume of the exothermic reaction agent and/or liquid for use in different ambient temperatures. This, however, would increase the amount of manufacturing required with resultant increased cost and would cause users difficulty in selecting the products.
It is therefore an object of the present invention to provide a self-heating foodstuff container which may prevent hot gases from spouting out of the container to thereby avoid the above difficulties for a user.
It is another object of the invention to provide a self-heating foodstuff container in which the quantity of thermal energy to be generated can be adjusted by a simple operation in order to adjust the temperature of the foodstuff.
A further object of the invention is to provide a self-heating foodstuff container in which a user may easily and securely supply a reaction inducing liquid to an exothermic reaction agent.
A still further object of the invention is the provision of a self-heating foodstuff container which conveniently may be used anywhere without the necessity of providing separate devices such as a liquid bottle.